Sharples said there was no doubt the leadership struggle between himself and Te Ururoa Flavell was a factor in the result.

The party would meet in the next few days to discuss its leadership before a decision at the party's annual meeting in a fortnight.

"I am concerned. My heart is the Maori Party. And the fact we started off with a whizz and a bang and now we are down to where we are now is a sad thing for me. So of course, I will be giving some thought to how I react to that."

The result is the latest problem for Prime Minister John Key's support parties. Act leader John Banks faces a private prosecution over election donations, Peter Dunne was forced to resign as a minister over leaked documents, and now the Maori Party leadership is in doubt.

Asked if he believed he should now retire, Sharples said the annual meeting was meant to resolve those issues.

"But it is about perception. People see us as a divided group and that would have been one of the factors that counted against us. We have to give that some attention and we will.

"I have to weigh up what I consider to be the best move for the party to regain its strength, what might be the best tactics or the thing that's stopping us growing our support."

Mana leader Hone Harawira said that the result sent a clear message to the Maori Party: "Hanging out with the National Party is a death wish in the Maori seats," he said.

Speaking on Maori Television, he said the door was open to the Maori Party to join Mana to try to hold on to the Maori seats.

Meka Whaitiri won the Ikaroa-Rawhiti by-election convincingly, securing 42 per cent of the vote - but still a long way short of the late Parekura Horomia's 6,000-vote majority in 2011.

The former Cabinet minister's death in office forced the by-election.

Whaitiri celebrated her win at Manutuke Marae, just outside Gisborne where she was born.

"I have learned as I have gone on through this campaign and had wonderful support from the party," she said.

Nikora won 25 per cent of the vote, ahead of Raihania on 20 per cent.

Voter turn-out was low - only 10,519 of the 33,000 voters registered bothered to vote. But Whaitiri's win will be a relief to the Labour Party which was down in a poll in the week before the by-election.

Some regarded the by-election as a test of leader David Shearer, who has campaigned intensively in the electorate over the past week.

The by-election was marred with accusations of intimidation against the Mana Party by the Maori Party, which is considering laying a complaint with the Electoral Commission. The commission confirmed the Maori Party had claimed voting irregularities at booths in Hastings and Wairoa.

In Flaxmere, the Maori Party objected because Mana Party scrutineers were sitting beside election staff handing out voting papers rather than behind them as required.

And at Wairoa School, a poll manager barred a Maori Party scrutineer for having the incorrect documents.